Project Summary Type 1 diabetes (T1D) is a burdensome chronic disease that requires a demanding self-management regimen to optimize glycemic control and prevent short- and long-term complications. Advances in insulin pumps and continuous glucose monitoring (CGM) technologies have enabled improved glycemic control and reduced risk of complications and have laid the groundwork for the arrival of closed loop systems ? the first of which became commercially available in 2017. Closed loop systems, which integrate an insulin pump and CGM to partially automate insulin delivery, represent a major paradigm shift in diabetes care such that people with T1D will offload some of the diabetes management burden to an automated system, resulting in tighter glucose control and better quality of life. However, a minority of adults (18-50) with T1D currently use CGM ? a core component of closed loop - and a concerning proportion quit CGM within the first year, which does not bode well for the adoption of closed loop. Low uptake and high discontinuation of CGM among adults with T1D signal the need for well-designed, tailored interventions that provide education, support and problem-solving skills to empower device users to work through physical, social, and other barriers to maximize benefit from advanced diabetes technologies. In this application, Molly Tanenbaum, PhD, proposes a series of studies with an overarching goal of developing advanced behavioral research skills while refining a comprehensive behavioral intervention package to equip adults with T1D with the resources and skills to maximize benefit and minimize daily interference from CGM, with application for closed loop system adoption. The specific aims in this career development award proposal are: 1) to deliver, iteratively refine a behavioral intervention package, ONBOARD (OvercomiNg Barriers & Obstacles to Adopting Diabetes Devices), in a small sample of adults with T1D using CGM, and then conduct a randomized controlled trial of ONBOARD comparing device use, health and psychosocial outcomes after adults with T1D receive the intervention versus CGM-only; and 2) to use qualitative interview data to adapt ONBOARD for adults initiating closed loop systems. Results from these studies will provide preliminary data to inform a larger trial of ONBOARD for CGM and closed loop adoption and sustained use in a future R01 application. Dr. Tanenbaum?s long-term career objective is to be an independent investigator with a programmatic line of research focused on optimizing use of emergent diabetes technology to improve health and quality of life outcomes for adults with T1D. The mentoring, coursework, and career development activities proposed in this 5-year training award will provide Dr. Tanenbaum with the advanced statistical training and experience conducting a randomized controlled trial ? skills necessary for a successful career as an independent behavioral diabetes researcher.